REDNASAJUCI / LECTURER :

Emil Kundra

(1) Astronomical Institute, Slovak Academy of Sciences,
059 60 Tatranská Lomnica

NAZOV / TITLE :


A circumbinary companion from Hipparcos-Gaia astrometry

ABSTRAKT / ABSTRACT :

We have investigated the astrometric motion of a source observed
by Gaia and Hipparcos. For our study, we used astrometric signatures
hidden within the proper motion anomaly (PMa), the excess of residuals
present in the renormalized unit weight error (ruwe), and the astrometric
excess noise (AEN). Astrometric signatures allow for the identification
of stellar binaries and hint toward companions with a mass in the planetary
domain. We ran a full MCMC with RV and PMEX astrometry, accounting for both
components. Our results prefer small masses, below 30 Mjup. The best fit has
a mass of 21 Mjup; the model does not exclude values of 30 Mjup or higher.
In the end, we are getting a result that matches well with what we found
from the light-time variations. The companion inferred from light-time
variations is totally compatible with the Gaia-Hipparcos astrometry.